Mycoplasma Genitalium (MGen): Symptoms, Testing, and Treatment in the UK

Mycoplasma genitalium, commonly referred to as MGen, is a bacterium that can be passed on through unprotected vaginal or anal sex. While it was only discovered in the 1980s, it is now recognised by the British Association for Sexual Health and HIV (BASHH) as a significant cause of reproductive health issues.

Unlike more famous STIs like chlamydia or gonorrhoea, MGen is unique because it lacks a cell wall. This makes it naturally resistant to many common antibiotics, such as penicillin, that work by attacking a bacterium's wall. In the UK, MGen is becoming a public health concern due to rising levels of antibiotic resistance, making correct diagnosis and targeted treatment essential.

A significant number of people carrying MGen will have no symptoms at all. However, when symptoms do occur, they often mimic other STIs. In the UK, patients frequently report the following:

Symptoms in Men

• Urethritis: Inflammation of the tube that carries urine (the urethra).
• Discharge: Watery or mucoid discharge from the penis.
• Painful Urination: A stinging or burning sensation when passing urine (dysuria).
• Testicular Pain: Occasionally, MGen can lead to inflammation of the testicles.

Symptoms in Women

• Vaginal Discharge: An unusual change in discharge.
• Pelvic Pain: Pain in the lower abdomen, particularly during or after sex.
• Intermenstrual Bleeding: Bleeding between regular periods or after intercourse.
• Cervicitis: Inflammation of the cervix.

If you visit a local sexual health clinic or use a standard home testing kit, MGen is often not included in the basic chlamydia and gonorrhoea screen. Because the bacterium grows very slowly, it cannot be identified using traditional culture methods. Instead, UK laboratories use a Nucleic Acid Amplification Test (NAAT).

NICE and BASHH guidelines suggest testing for MGen specifically if you have symptoms of urethritis or pelvic inflammatory disease (PID) that have not responded to standard treatments. Men typically provide a first-catch urine sample, while women are usually advised to provide a vaginal swab. It is important to wait at least two weeks after potential exposure before testing to ensure an accurate result.

Treating MGen in the UK has become more complex. In the past, a single dose of azithromycin was often used, but the bacterium has developed high levels of resistance to this drug. Current BASHH guidelines typically recommend a two-stage antibiotic approach.

The first stage usually involves a course of doxycycline to reduce the bacterial load, followed by a specific second antibiotic like azithromycin (if the strain is sensitive) or moxifloxacin. It is vital to complete the entire course as prescribed, even if symptoms disappear early, to prevent further resistance. Patients must also avoid sexual contact until they—and their partners—have finished treatment and received a 'test of cure' approximately five weeks later.

Sexual health can be a sensitive topic, and many patients prefer the privacy of a digital consultation. You should consider an online GP appointment if you are experiencing persistent discharge, pain during urination, or pelvic discomfort, especially if previous STI treatments have failed.

Speaking to an online GP allows you to discuss your symptoms in a calm, confidential environment. A doctor can review your history, explain the specific testing requirements for MGen, and provide a private prescription if appropriate. They can also provide a sick note if your symptoms or treatment side effects require time away from work. For those in the UK, this serves as a convenient alternative to waiting for a walk-in clinic appointment.

Left untreated, MGen can lead to serious long-term health complications. In women, the infection can spread to the fallopian tubes and uterus, causing Pelvic Inflammatory Disease (PID). PID is a leading cause of ectopic pregnancy and tubal infertility. In men, chronic inflammation of the urethra can lead to discomfort and, in rare cases, affects fertility. Early detection and adherence to NHS-aligned treatment protocols are the best ways to protect your future reproductive health.